Heat Treating help needed

G

godogs57

Joined
Apr 16, 2004
Messages
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Been making knives for awhile now, but just purchased my first oven yesterday. It was too good of a deal to pass up, so now I am able to heat treat my knives instead of sending them off. What I need is some "formulas" for heat treating that work for you. Folks on this forum have been so helpful with other questions in the past, and it is sincerely appreciated!

I will be heat treating 440C, ATS-34 and some damascus for now. As I understand, each type of steel is different in how its hardened. The guy that I bought my oven from (Brand new Evenheat Perfect Fire, 22.5 " model) only heat treated 440C, and had this formula: put blades in, bring it up to 1900 degrees ASAP, about an hour and 20 minutes, hold for 20 minutes, and then I dont know what he did with it then...I suppose he let the blades cool down to room temp? I don't have a clue.

Anyway, if anybody would be willing to let me in on their "recipie" for 440C, ATS-34 and damascus, I would sure appreciate it. My best friend that heat treats my 440C blades heat treated a batch of ATS-34 blades, without me telling him so......they all came out at 58 Rockwell, so perhaps there is not that much difference in 440C and ATS-34...let me know if there is or is not that much difference. I also have some blades made up of Thunderforged twist damascus, and some ATS-34 damascus that I would appreciate any ideas on as well.

Thanks so much in advance!
 
It is way too much to answer all that about all those steels in one setting. Tell us which steel you prefer to HT first and we can start from there. I have successful directions for all that you mentioned. There is much more to learn about HT'ing than only times and temperatures. Is it 440C you wish to start with? Let us know and we can get started.

RL
 
I posted before looking at your profile. I have removed my postings. You don't even want us to know where you are from. I don't know you from Adam and we are at war.

RL
 
Mr. Rlinger and Mr. Bump, I have been on this forum for about month now. I signed up to get a user name and password at that time. I thought I had completed a profile at that time, but apparantly did not. If profiles are that important to you, I certainly understand, and agree with RLinger...we are at war. I am 46 years old, live in Leesburg, Georgia, and am US Army Ranger qualified. I have been making knives seriously for 10 or so years, having made right at 500 knives, but, until now, have had a friend do my heat treating. Hence, my asking for advice from people that knew far more than I about certain aspects of our trade. I will ensure that I go back and review my profile to include those items in order that this does not happen in the future.

Perhaps I was too quick when I said "thanks in advance" in my first post. If you make it to the blade show, stop by and say hey and I will go buy you a coke or something....just look for the ugliest guy you can imagine and slap me upside the head.

Take care.
 
Well....the Internet is a place with many hidden dangers,,,

I dont alow my kids to ever write down their real names or their real home town on the sites they go to.

Now Im an adult, I can do as I think best on a case by case situation. As such once I was a member of Blade Forums for a while I did let on to others where I lived, however, this was after I learned a few things first.
Best to be slow about such things I believe. I would rather be called a guy who must have a secret, rather than a guy who gets told later I should have kept more things secret.

Some guys like to always use their real names, some guys like to splash around the Web their real phone number and their real home address.....

To each his own.
 
Godog, Welcome to shoptalk. We are generally a big happy family and welcome new members. Maybe in this suspicious day we live in we need a more complete profile. Sorry if I sounded hostile.

Heat-treat information is hard to find as most had to earn it the hard way. Roger for one has spent endless hours and electricity compiling his data. The great ones do it this way. You can get a sheet that covers most all the air-hardening steels from Texas Knifemakers Supply. They sell the Even Heat and offer the sheet for free. Sorry I dont have their number handy but they have a web site.

Let us know how you do.
 
Thanks Bruce.....will run into the folks at Texas Knifemakers Supply in a couple of weeks at the blade show...perhaps they will have that information there. DaQo'tah Forge, your comments were appreciated.

Take Care.
 
Rodger and Bruce, my profile isn't quite correct as both of you know. I did get around to posting my real name on this forum a while back but it was the first time ever on the INTERNET.

It's not so much secrecy as it is privacy with me. Not a day goes by that I don't get an email for AAABA DABA in far off somewhere who wants to buy 6 million dollars worth of computers for his government and will pay using his government visa :rolleyes:
Or from EBAY who says someone is using my account and they will investigate it if I only give them my password and credit card number :rolleyes: :rolleyes:

The list goes on. If it were secure and I could control who looked at it, I would gladly fill out a complete profile.
 
I welcome you also. Sorry about all that delay and very glad you undertood without getting upset at me. Here we go:
-------------

Okay, 440C. I'll grab my notes on the last couple I did in a moment but for now .... Your buddy may do well, however as you remembered what he told you, some things were missing. What I say next is NOT particular to 440C. It is best to place the blade (the steel) in the cool oven and ramp slowly the oven temperature to a pre-heat temperature that is particular to that steel (some steels pre-heat at different temperatures). Hold at pre-heat for a few minutes. This will vary according to how slowly the ramp to pre-heat was but should not exceed 15 minutes after the steel equalizes at pre-heat, regardless. After pre-heating the oven should be ramped as quickly as possible to the austenitizing temperature and the steel should soak for a period of time; after which the steel is IMMEDIATELY quenched and then allowed to still air cool to a temperature ready for placing in PRE-HEATED tempering or 'snap tempering oven.

The reason for pre-heating is because the steel will expand at pre-heat and the steel will contract at austenitizing. So, we want all the steel cross section to equalize at the pre-heat temperature before austenitizing. If not allowed to do this some portions of the work piece (the blade) may both contract and expand simultaniously.

Now I will retrieve my notes on what I have done with 440C and be back to you with a receipe.

RL
 
Here is one for you I think will work well:

This one has a complex pre-heat (two pre-heat temperature levels that are both performed).

Place the blade in the cool oven.

Ramp the oven at a rate of 550 F per hour to a pre-heat of 1150 F and hold for 7 minutes.

(from 1150 F) Ramp 550 F per hr. to 1400 F and hold 7 min.

Ramp as fast as the oven can to austenitizing, 1850 F and 'soak' 25 min.

* Rapid air quench to hand warm (try to guess at about 125 F by touch. If you can hold it and it is warm but not too far from too warm - that is 'hand warm')

Place in pre-heated tempering oven IMMEDIATELY before the steel falls below hand warm.

Temper at 400 F / 1 hr.

Still air cool to room temperature.

Temper again at 375 F / 1 hr.

Probably get about 57 HRc on that without a cryogenic treatment. With a cryogenic treatment (which would be performed after quench and before any tempering except snap tempering I would expect abouit 58 HRc minimum).

Will your oven perform those ramping function?

Another thing not mentioned yet is that the steel (stainless at those long soak periods) will need to be atmosphere controlled so that scaling and decarboration is not too deep. Do you have stainless steel foil wrap for heat treating these steels? You will need your stainless blades protected from oxygen while soaking at such temperatures for so long.

One other thing that comes immediately to mind that I should briefly mention now is 'stress relieving'. Before the actual heat treat you may elect to stress relieve your blade after grinding it. That is a procedure where you will heat it slowly to a particular temperature and allow to cool relatively slowly (usually still air cooling to room temperature).

* do not quench your air quench blades in still air. Quench in a rapid air flow. Use a fan or better make a tunnel for the fan's air to flow through so that the flow is more concentrated. You can also oil quench many or all air quench steels. Use your experience to determine how best to quench. On massive blades I prefer to oil quench because I do not yet have the air flow for massive blades. I prefer air quench for air quench steels but will oil quench with good result when necessary.

RL
 
Thanks for your reply...it is appreciated. Prior to receiving your reply, I tried out the oven today to sort of get a benchmark to go by in the future. My buddy that heat treats my stuff gave me some info to start with, and, then seeing where I got, we can sort of refine the process from there.

I got some scraps of 440C and ATS-34, and put them in the oven, in the brick "holder" (gosh, if I happen to call something by the wrong name, please forgive me, as I know so little about heat treating...I now have one day experience at this part of the game). I then turned the oven on, and ran the old program still in the computer of the oven....up to 1900 degrees and hold for 20 minutes. At that point, I took the scraps out, placed them in front of a fan to cool off. I was planning on then putting them back in the oven once it dropped to 1050 degrees to temper them....once they cooled, I checked the hardness to see where I was at so to speak. My buddy said I should be somewhere around 62 or so...then back in at 1050 to temper. Well, both the 440C and ATS-34 scraps did not harden to 62 as expected....the 440C scraps were 57 and the ATS-34 were 58. My buddy then told me that, given that it did not get them up to 62, there was no use to put them back in at 1050 to temper them....I need to work on getting the hardness up some before we tackle tempering....

Still learning this black magic stuff regarding heat treating...I appreciate your help.
 
Lower your 440C from 1900 to 1850 and raise your ATS-34 from 1900 to 1950. I would not temper those so high. Temper 440C at 400 and the ATS-34 at 550 - 600. Increase the soak time from 20 to 25 minutes. It is better to over soak a little than to under soak a little. See what happens. Do not waste time getting the steel to rapid air quench.

I do not like to Rockwell untempered steel. It could be dangerous since in the 'as quenched' state the steel is unstable. I usually snap temper and then Rockwell before putting in cryo.

You won't be able to properly use your HT'ing oven for the first temper because it will not cool back soon enough. For the 440C you can use a toaster oven that is monitored by a oven thermometer. You can hold the ATS-34 at about 220 F in the toaster oven until the HT'ing oven cools back enough to temper at about 550 F. Always use a oven thermometer in the toaster oven or kitchen oven.

RL
 
godogs, did you wrap your steel before you hardened? if not, did you grind the scale off into clean metal before you Rockwelled?
 
Fitzo reminds us of a good piece of advise. Rockwell testings are linkely to be low if the decarburation and scaling is not ground off. We want to test the solid hard surface. The surface should also be flat to the tester. I think I have even noticed a slight difference in Rockwell from testing straight out of temper and grinding off the thin oxidation caused by tempering.

RL
 
Again, your comments are appreciated. I tried again tonight and did not soak as long (15 minutes once I got to 1800 degrees) and that apparently was not in the right direction, so to speak, as the 440 C rockwelled at 55 and the ATS-34 went 52. Now that I have seen your last comments, I think I did not soak as long as I should have. I am learning that each person's oven is different, and you have to tweek what other persons say to fit your oven's situation.

I am grinding off the scale before testing, and am quickly removing the pieces from the oven to sit in front of the fan...not wasting any time. I will assume that the tempering for one hour, as mentioned in your previous email, unless told differently.

Fitzo, I appreciate your comments and help as well...take care. Will let y'all know how this comes out. Again, thanks!
 
Couple of comments, food for thought type.
Stay away from the high temp tempers for ATS-34. You can do it high or low but the high one will give you much less corrosion resistance.
Have you tested you Rockwell tester?
Put a small heat consumable (piece of paper, cigarette butt, etc) in the foil package to kill any oxygen in it.
Have you tested the accuracy of the oven? One of mine is 75° low and one is 50° high. Long as you know it and test them occasionally, not a problem.
I'm sure I'll think of more little things :)
Welcome to the forum.
 
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